# Can tsunamis be small waves?

In the open ocean, tsunami waves can be small and may even be undetectable by a boat at the surface. But as the tsunami approaches land, the ocean gets progressively shallower and all the wave energy that extended thousands of feet to the bottom of the deep ocean gets compressed. The displaced water needs to go somewhere.

## How many waves are usually in a tsunami?

• A tsunami is not a single wave but a series of waves, also known as a wave train. The first wave in a tsunami is not necessarily the most destructive. Tsunamis are not tidal waves. • Tsunami waves can be very long (as much as 60 miles, or 100 kilometers) and be as far as one hour apart.

Tsunamis with runups over one meter (3.28 feet) are particularly dangerous to people and property. Yet, smaller tsunamis can also be dangerous . Strong currents can injure and drown swimmers and damage and destroy boats and infrastructure in harbors.

Largest/highest tsunami The largest tsunami ever recorded occurred on 9 July 1958 in Lituya Bay, Alaska. An earthquake measuring 8.3 on the Richter scale shook loose around 40 million cubic yards.. The wave caused widespread devastation, with an official count of 18,550 people confirmed to be killed/missing.

Tsunamis have a small wave height offshore, and a very long wavelength (often hundreds of kilometres long, whereas normal ocean waves have a wavelength of only 30 or 40 metres), which is why they generally pass unnoticed at sea, forming only a slight swell usually about 300 millimetres (12 in) above the normal sea surface.

With wave speeds that can reach as much as 435 miles per hour, a tsunami can travel as far inland as 10 miles, depending on the slope and the shape of the shoreline that it is traveling across. Ships traveling in the deep ocean may pass over a tsunami and not even notice it because a tsunami can cause the waves to be as little as 2 feet high where the water is very deep.

## Is a tsunami and a tidal wave the same thing?

These terms, tidal wave and tsunami, refer to the same natural phenomenon; an unusually large ocean wave caused by an earthquake, underwater landslide, or other large disturbance. They are not, however, used interchangeably and tsunami is now the preferred term.

We discovered tsunamis are sometimes referred to as tidal waves. This once-popular term derives from the most common appearance of a tsunami, which is that of an extraordinarily high tidal bore. Tsunamis and tides both produce waves of water that move inland, but in the case of a tsunami, the inland movement of water may be much greater, giving the impression of an incredibly high and forceful tide.